Lock-stitch sewing machine



2l, 1935. H. coRRALL Er AL 2,002,172

LOCK STITCH SEWING MACHINE l Filed Aug. 25, 195:5 2 sneetsfsneet 1.

. FIG. 4.

FIG. l

Fre E 'May 21, 1935- H. coRRALL n AL n 2,002,172

LOCK STITCH SEWING MACHINE Filed Aug. 25, 193s 2 sheets-sheet 2 :saL

' @Franny` Patented M., 21, 1935 PATENT OFFICEV LOCK-STITCH SEWING .Herbert Canali, Helensburgh, and James Reggie,

Clydebank, Scotland,

assignors to The Singer Manufacturing Company, Elizabeth, N. J., l. corporation of New Jersey Application August 25,

1933, Serial No. 686,666

In Great Britain September 12, 1932 10 Claims.

This invention relates to improvements in lockstitch sewing machines and has for an object to provide a hook and bobbin-case construction in which the bearing surfaces may be made of maxi- 5 mum dimensions and in which the parts presenting such surfaces can be readily replaced.

Another object of the invention is to provide simplified and improved means for lubricating the bobbin-case raceway in the hook.

More particularly the invention is applicable to rotary hook lock-stitch sewing machines, such as described for example in United States Patent No. 1,400,141, of Dec. 13, 1921, used largely for the darning or mending of sacks containing a large amount of abrasive matter.

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

In the accompanying drawings Fig. 1 is a transverse vertical section through the cylinder-bed of a sewing machine embodying the invention, showing the hook mechanism in elevation. Fig. 2 is a top plan view with the cloth-plate removed. Fig. 3 is a vertical section through the hook and bobbin-case on the line 3--3, Fig. 2. Fig. 4 is a horizontal section through the hook body and lubricating-reservoir. Fig. 5 is a section on the line 5-5, Fig. 1. Fig. 6 is a section on the line 6-"6, Fig. 5. Fig. 7 is a perspective view of the bobbin-case rotation-restraining bar. Fig. 8 is a disassembled perspective view of the rotary hook. Fig. 9 is a perspective view of the body element of the hook showing the slot for reception of a lubricant pad. Fig. l0 is a'perspective view of the felt pad which is received in the slot shown in Fig; 9 in the hook body member. Fig. 11 is a disassembled perspective view of the bobbin-case, and Fig. 12 is a perspective view of the bobbin.

The cylinder bed or work-supporting arm I of the sewing machine has journaled in it the rotary hook shaft 2 to which is secured the cup-shaped hook-body 3 preferably made as a drop forging and having a machined rim-face'l, cylindrical seat 5 and shoulder 6.

Detachably secured to the seat 5 by screws 1 is the plain cylindrical or annular race-forming member 8 having a loop-seizing beak II and heel Il between which is a gap bridged by the guard member Il which is secured to the member 8 by screws I2. The race-forming member 3 may be cheaply made from tubular stock of suitable st eel, such as high carbon steel containing chromium, which may be ground to size. The hooks at present in use are comparatively expensive to manufacture in that they must be machined from stock equal to the largest diameter of the hook.

The bobbin-case I3 is correspondingly provided with a detachable rim I4 presenting a flat end face I4 and a cylindrical bearing rib I5 having l0 its bearing in the raceway in the hook and having its flat face I4' secured to the body of the bobbin-case I3 by screws; the bobbin-case being partially received within the cylindrical bearing rib I5.

As the result of a practical test it is found that with the adoption of the invention the life of thebody-portions of the hook and bobbincase is practically indefinite, while the cost of replacement of the worn portions is-reducedto a minimum.

The bobbin-case I3 is formed on its front or exposed face with a projecting diametrical rib I6 the upperend of which is formed with a vertical needle-clearance slot I6' and is received in the notch II in the rotation-restraining bar I8 which bridges the space between the side walls of the work-arm I, below the usual cloth-plate `|9 formed with the needle-hole 20 for the reciprocatory needle 2l. In the prior construction according to said U. S. Patent No. 1,400,141, the bobbin-case is held against rotation by a projection on the rotation-restraining bar entering a rnotchor slot in the bobbin-case in which the needle reciprocates. On accountkof the presence of the needle in this notch, the projection on the rotation-restraining bar cannot enter the notch deeply enough to avoid accidental release of the bobbin-case from the projection when the hook and bobbin-case become worn. In the present instance, by providing the bobbin-case with a projection having a needle-clearance notch and entering a notch in the rotation-restraining bar, the depth of the engagement between the projection on the bobbin-case and the rotation-restraining bar may be materially increased without regard to the needle, and hence increased life of the bobbin-case is realized and the mainte` nance of freedom between the hook and the bobbin-case permitting passage of the needle-loops around the bobbin-case and ready tightening of the stitch is ensured. The bobbin-case I3 is provided with the usual central post I3' on which is removably journaled the usual bobbin I3".

As the hook illustrated is of the open race- 55 yieldingly against the outside face of the bobbincase. The hub Il' bf the latch-arm 2l is formed at its lower side -with a ilat face 3l which is yieldingly engaged by the free end of a ilat spring Il secured at its other end to the stud pin 28. Ihe latch-arm 3l is thus 'yieldingly held in its bobbin-case-retaining position, shown in full unes in rig. 1, but may be instantly swung to* dotted line position, Fig. 1, to free the bobbincase for removal from the hook.

Preferably. provision is made for automatic lubrication of the raceway presented by the hook. To this end a small cup-shaped lubricant container or reservoir 22 is secured within the workarm -I adjacent to the rear side of the hook body l by means of the tubular .screw 23 passing through the side wall of the work-arm i and through which oil may be introduced into the container. Projecting laterally from the container 22 is a tube 2l through which projects a wick 25. vThere is milled in the hook-body 3, Fig. 9, a slot 2l for reception of a felt pad or wickvk 21 leading to the hook raceway. As the hook revolves, the rotating wick 21 wipes against the-end of thestationary wick 2S and absorbs oil therefrom which oil is conducted to the tip end of the wick 2"v and applied to the bearing rib Il of the bobbin-case r.journaled in the hook raceway. v

'Ihe invention is not to be understood as limited'to the details of construction and relative arrangements of parts shown and described, as various modiiications may obviously be readily made byjthose skilled inthe art within the scope of the invention.

Having thus set forth the nature of the invention, what we claim herein is:-

l. In rotary hook mechanism for lock-stitch sewing machines, a rotary hook and a bobbincase Journaled therein, said hook and bobbincase comprising body members and complementary bearing rings detachably secured each to a respective one of `said body members.

2. In rotary hook mechanism for lock-stitch sewing machinesfa cup-shaped hook-body, a

\ bobbincase`body received therein, a peripheral bearing rib detachably mountedv on said bobbincase-body and 'a raceway-forming ring-shaped member detachably mounted on said hook-body and in which said lbohbin-case bearing rib is joumaled, said member being formed with a' loop- 3. The combination with a rotary hook presenting a raceway, of a bobbin-case comprising a ring-shaped bearing member journaled in said raceway, and a bobbin-case body detachably secured to said bearing member.

4. 'Ihe combination with a rotary hook pre seating a raceway, of a bobbin-case comprising a ring-shaped bearing member `journaled in said raceway, and formed with a flat face portion and a cylindrical bearing rib portion, and a bobbincase body partially received within said cylindrical bearing rib portion anddetachably secured to said fiat face portion.

5. In rotary hook mechanism for lock-stitch sewing machines, a reciprocatory-needle, a rotary hook, a bobbin-case received within and having .a bearing engagement with said hook, said bobbincase having at its outer side face a rotation restraining projection having parallel side-walls and formed with an open sided needle-clearance slot, and a stationary rotation restraining element having a recess with parallel side-walls entered by said bobbin-case projection.

6. In a sewing machine, a rotary hook, a hook shaft, a stationary bobbin-case having a bearing in said hook, said hook having an oil passageway leading from the rearward side thereof to said bearing, and means external to and independent of said shaft for supplying oil to said passageway while the hook is running.

7. In a sewing machine, a frame, a rotary hook,

a hook-shaft, a stationary bobbin-case having a bearing in said hook, said hook having a rotating wick in communication with said and exposed at the rear of said hook at a distance away from said hook-shaft, a stationary oil reservoir secured to said frame, and a stationary wick projecting from said reservoir into the path of circular movement oi said exposed rotating wick.

8. In a sewing machine, a hollow frame, anV

oil reservoir disposed within said hollow frame, a tubular screw passing through a wall of said frame and threaded into said oil reservoir, a stationary wick projecting from said reservoir, a rotary hook journaled in said frame and disposed adjacent said stationary wick, said hook having a raceway, a rotary wick carried by said hook and leading to said raceway, said rotary wick being adapted to wipe against said stationary wick, and a stationary bobbin-case journaled in said raceway. e

9. In a sewing machine, a rotary hook, a hookshaft, a hook-shaft bearing, a bobbin-case having a bearing in said hook, a rotary'wick carried by said hook for feeding oil to said bobbin-case bearing, and stationary means for feeding oil to said rotary wick at a point externally of said hookshaft and hook-shaft bearing while the hook is running.

10. In a rotary hook sewing machine, a cup shaped rotary hook body having a cylindrical seat and a groove extending across said seat in a direction parallel to the axis ofl rotation of said hook-body, a cylindrical ring-shaped member having a loop-seizing beak. said member 4 

